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Three families suspected of distal hereditary motor neuropathy underwent genetic screening with the aim to identify the molecular defect underlying the disease. The description of the identification reflects the shift in molecular diagnostics that was made during the last decades. Our candidate gene approach yielded a known pathogenic variant in BSCL2 (p.Asn88Ser) in one family, and via a CMT-capture, in HSPB1 (p.Arg127Trp), in addition to five other variations in Charcot-Marie-Tooth-related genes in the proband of the second family. In the third family, using whole exome sequencing, followed by linkage-by-location, a three base pair deletion in exon 33 of MYH7 (p.Glu1508del) was found, a reported pathogenic allele albeit for a myopathy. After identification of the causative molecular defect, cardiac examination was performed for patients of the third family and this demonstrated abnormalities in three out of five affected family members. Heterogeneity and expansion of clinical phenotypes beyond known characteristics requires a wider set of genes to be screened. Whole exome/genome analysis with limited prior clinical information may therefore be used to precede a detailed clinical evaluation in cases of large families, preventing screening of a too narrow set of genes, and enabling the identification of novel disease-associated genes. In our cases, the variants had been reported, and co-segregation analysis confirmed the molecular diagnosis.

This study shows that gain-of-function variants in KLHL24 causing EBS and DCM, do not only originate in the start-codon and suggest that any nonsense-inducing variant affecting nucleotides c.4_84 will likely cause the same effect on protein level and a similar potential lethal phenotype.

Background - Variants within the alpha-tropomyosin gene (TPM1) cause dominantly inherited cardiomyopathies, including dilated (DCM), hypertrophic (HCM) and restrictive (RCM) cardiomyopathy. Here we investigated whether TPM1 variants observed in DCM and HCM patients affect cardiomyocyte physiology differently.Methods - We identified a large family with DCM carrying a recently identified TPM1 gene variant (T201M) and a child with RCM with compound heterozygote TPM1 variants (E62Q and M281T) whose family members carrying single variants show diastolic dysfunction and HCM. The effects of TPM1 variants (T201M, E62Q or M281T) and of a plasmid containing both the E62Q and M281T variants on single-cell Ca2+ transients (CaT) in HL-1 cardiomyocytes were studied. To define toxic threshold levels, we performed dose-dependent transfection of TPM1 variants. In addition, cardiomyocyte structure was studied in human cardiac biopsies with TPM1 variants.Results - Overexpression of TPM1 variants led to time-dependent progressive deterioration of CaT, with the smallest effect seen for E62Q and larger and similar effects seen for the T201M and M281T variants. Overexpression of E62Q/M281T did not exacerbate the effects seen with overexpression of a single TPM1 variant. T201M (DCM) replaced endogenous tropomyosin dose-dependently, while M281T (HCM) did not. Human cardiac biopsies with TPM1 variants revealed loss of sarcomeric structures.Conclusion - All TPM1 variants result in reduced cardiomyocyte CaT amplitudes and loss of sarcomeric structures. These effects may underlie pathophysiology of different cardiomyopathy phenotypes. (C) 2020 The Authors. Published by Elsevier B.V.

Recent advancements in next generation sequencing (NGS) technology have led to the identification of the giant sarcomere gene, titin (TTN), as a major human disease gene. Truncating variants of TTN (TTNtv) especially in the A-band region account for 20% of dilated cardiomyopathy (DCM) cases. Much attention has been focused on assessment and interpretation of TTNtv in human disease; however, missense and non-frameshifting insertions/deletions (NFS-INDELs) are difficult to assess and interpret in clinical diagnostic workflow. Targeted sequencing covering all exons of TTN was performed on a cohort of 530 primary DCM patients from three cardiogenetic centres across Europe. Using stringent bioinformatic filtering, twenty-nine and two rare TTN missense and NFS-INDELs variants predicted deleterious were identified in 6.98% and 0.38% of DCM patients, respectively. However, when compared with those identified in the largest available reference population database, no significant enrichment of such variants was identified in DCM patients. Moreover, DCM patients and reference individuals had comparable frequencies of splice-region missense variants with predicted splicing alteration. DCM patients and reference populations had comparable frequencies of rare predicted deleterious TTN missense variants including splice-region missense variants suggesting that these variants are not independently causative for DCM. Hence, these variants should be classified as likely benign in the clinical diagnostic workflow, although a modifier effect cannot be excluded at this stage.

Background: TTN (Titin), the largest protein in humans, forms the molecular spring that spans half of the sarcomere to provide passive elasticity to the cardiomyocyte. Mutations that disrupt the TTN transcript are the most frequent cause of hereditary heart failure. We showed before that TTN produces a class of circular RNAs (circRNAs) that depend on RBM20 to be formed. In this study, we show that the back-splice junction formed by this class of circRNAs creates a unique motif that binds SRSF10 to enable it to regulate splicing. Furthermore, we show that one of these circRNAs (cTTN1) distorts both localization of and splicing by RBM20. Methods: We calculated genetic constraint of the identified motif in 125 748 exomes collected from the gnomAD database. Furthermore, we focused on the highest expressed RBM20-dependent circRNA in the human heart, which we named cTTN1. We used shRNAs directed to the back-splice junction to induce selective loss of cTTN1 in human induced pluripotent stem cell–derived cardiomyocytes. Results: Human genetics suggests reduced genetic tolerance of the generated motif, indicating that mutations in this motif might lead to disease. RNA immunoprecipitation confirmed binding of circRNAs with this motif to SRSF10. Selective loss of cTTN1 in human induced pluripotent stem cell–derived cardiomyocytes induced structural abnormalities, apoptosis, and reduced contractile force in engineered heart tissue. In line with its SRSF10 binding, loss of cTTN1 caused abnormal splicing of important cardiomyocyte SRSF10 targets such as MEF2A and CASQ2 . Strikingly, loss of cTTN1 also caused abnormal splicing of TTN itself. Mechanistically, we show that loss of cTTN1 distorts both localization of and splicing by RBM20. Conclusions: We demonstrate that circRNAs formed from the TTN transcript are essential for normal splicing of key muscle genes by enabling splice regulators RBM20 and SRSF10. This shows that the TTN transcript also has regulatory roles, besides its well-known signaling and structural function. In addition, we demonstrate that the specific sequence created by the back-splice junction of these circRNAs has important functions. This highlights the existence of functionally important sequences that cannot be recognized as such in the human genome but provides an as-yet unrecognized source for functional sequence variation.

Background: Mutations in RBM20 (RNA-binding motif protein 20) cause a clinically aggressive form of dilated cardiomyopathy, with an increased risk of malignant ventricular arrhythmias. RBM20 is a splicing factor that targets multiple pivotal cardiac genes, such as Titin (TTN) and CAMK2D (calcium/calmodulin-dependent kinase II delta). Aberrant TTN splicing is thought to be the main determinant of RBM20-induced dilated cardiomyopathy, but is not likely to explain the increased risk of arrhythmias. Here, we investigated the extent to which RBM20 mutation carriers have an increased risk of arrhythmias and explore the underlying molecular mechanism. Methods: We compared clinical characteristics of RBM20 and TTN mutation carriers and used our previously generated Rbm20 knockout (KO) mice to investigate downstream effects of Rbm20-dependent splicing. Cellular electrophysiology and Ca 2+ measurements were performed on isolated cardiomyocytes from Rbm20 KO mice to determine the intracellular consequences of reduced Rbm20 levels. Results: Sustained ventricular arrhythmias were more frequent in human RBM20 mutation carriers than in TTN mutation carriers (44% versus 5%, respectively, P =0.006). Splicing events that affected Ca 2+ - and ion-handling genes were enriched in Rbm20 KO mice, most notably in the genes CamkIIδ and RyR2. Aberrant splicing of CamkIIδ in Rbm20 KO mice resulted in a remarkable shift of CamkIIδ toward the δ-A isoform that is known to activate the L-type Ca 2+ current ( I Ca,L ). In line with this, we found an increased I Ca,L , intracellular Ca 2+ overload and increased sarcoplasmic reticulum Ca 2+ content in Rbm20 KO myocytes. In addition, not only complete loss of Rbm20, but also heterozygous loss of Rbm20 increased spontaneous sarcoplasmic reticulum Ca 2+ releases, which could be attenuated by treatment with the I Ca,L antagonist verapamil. Conclusions: We show that loss of Rbm20 disturbs Ca 2+ handling and leads to more proarrhythmic Ca 2+ releases from the sarcoplasmic reticulum. Patients that carry a pathogenic RBM20 mutation have more ventricular arrhythmias despite a similar left ventricular function, in comparison with patients with a TTN mutation. Our experimental data suggest that RBM20 mutation carriers may benefit from treatment with an I Ca,L blocker to reduce their arrhythmia burden.

We report a family in which an autosomal dominantly inherited Charcot-Marie-Tooth (CMT) disease type 2 was suspected. The affected family members (proband, sister, father, and paternal aunt) showed intrafamilial clinical variability. The proband needed walking aids since adolescence because of generalized muscle weakness. The sister showed the same symptoms although to a lesser extent. The father and paternal aunt had foot deformity and atrophy of lower legs. A homozygous GDAP1 mutation was found in the proband and in the sister. Further testing showed compound heterozygous GDAP1 mutations in the father and paternal aunt. In this CMT2 family with a pseudodominant inheritance pattern DNA-diagnostics revealed the presence of both homozygous and compound heterozygous GDAP1 mutations. We recommend including multiple family members in genetic studies on CMT families.

Aims Truncating titin mutations (tTTN) occur in 25% of dilated cardiomyopathy (DCM) cases, but the phenotype and severity of disease they cause have not yet been systematically studied. We studied whether tTTN variants are associated with a clinically distinguishable form of DCM. Methods and results We compared clinical data on DCM probands and relatives with a tTTN mutation (n = 45, n = 73), LMNA mutation (n = 28, n = 29), and probands who tested negative for both genes [idiopathic DCM (iDCM); n = 60]. Median follow-up was at least 2.5 years in each group. TTN subjects presented with DCM at higher age than LMNA subjects (probands 47.9 vs. 40.4 years, P = 0.004; relatives 59.8 vs. 47.0 years, P = 0.01), less often developed LVEF

The first human mutations in GATA6 were described in a cohort of patients with persistent truncus arteriosus, and the phenotypic spectrum has expanded since then. This study underscores the broad phenotypic spectrum by presenting two patients with de novo GATA6 mutations, both exhibiting complex cardiac defects, pancreatic, and other abnormalities. Furthermore, we provided a detailed overview of all published human genetic variation in/near GATA6 published to date and the associated phenotypes (n = 78). We conclude that the most common phenotypes associated with a mutation in GATA6 were structural cardiac and pancreatic abnormalities, with a penetrance of 87 and 60%, respectively. Other common malformations were gallbladder agenesis, congenital diaphragmatic hernia, and neurocognitive abnormalities, mostly developmental delay. Fifty‐eight percent of the mutations were de novo, and these patients more often had an anomaly of intracardiac connections, an anomaly of the great arteries, and hypothyroidism, compared with those with inherited mutations. Functional studies mostly support loss‐of‐function as the pathophysiological mechanism. In conclusion, GATA6 mutations give a wide range of phenotypic defects, most frequently malformations of the heart and pancreas. This highlights the importance of detailed clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.

Variants in the KIF1A gene can cause autosomal recessive spastic paraplegia 30, autosomal recessive hereditary sensory neuropathy, or autosomal (de novo) dominant mental retardation type 9. More recently, variants in KIF1A have also been described in a few cases with autosomal dominant spastic paraplegia. Here, we describe 20 KIF1A variants in 24 patients from a clinical exome sequencing cohort of 347 individuals with a mostly 'pure' spastic paraplegia. In these patients, spastic paraplegia was slowly progressive and mostly pure, but with a highly variable disease onset (0-57 years). Segregation analyses showed a de novo occurrence in seven cases, and a dominant inheritance pattern in 11 families. The motor domain of KIF1A is a hotspot for disease causing variants in autosomal dominant spastic paraplegia, similar to mental retardation type 9 and recessive spastic paraplegia type 30. However, unlike these allelic disorders, dominant spastic paraplegia was also caused by loss-of-function variants outside this domain in six families. Finally, three missense variants were outside the motor domain and need further characterization. In conclusion, KIF1A variants are a frequent cause of autosomal dominant spastic paraplegia in our cohort (6-7%). The identification of KIF1A loss-of-function variants suggests haploinsufficiency as a possible mechanism in autosomal dominant spastic paraplegia.

BackgroundMutations in genes encoding ion channels or sarcomeric proteins are an important cause of hereditary cardiac disease. However, the severity of the resultant disease varies considerably even among those with an identical mutation. Such clinical variation is often thought to be explained largely by differences in genetic background or ‘modifier genes’. We aimed to test the prediction that identical genetic backgrounds result in largely similar clinical expression of a cardiac disease causing mutation, by studying the clinical expression of mutations causing cardiac disease in monozygotic twins.MethodsWe compared first available clinical information on 46 monozygotic twin pairs and 59 control pairs that had either a hereditary cardiomyopathy or channelopathy.ResultsDespite limited power of this study, we found significant heritability for corrected QT interval (QTc) in long QT syndrome (LQTS). We could not detect significant heritability for structural traits, but found a significant environmental effect on thickness of the interventricular septum in hypertrophic cardiomyopathy.ConclusionsOur study confirms previously found robust heritability for electrical traits like QTc in LQTS, and adds information on low or lacking heritability for structural traits in heritable cardiomyopathies. This may steer the search for genetic modifiers in heritable cardiac disease.

Contains fulltext : 204157.pdf (Publisher’s version ) (Closed access) BACKGROUND: Neuromuscular disorders (NMDs) are clinically and genetically heterogeneous. Accurate molecular genetic diagnosis can improve clinical management, provides appropriate genetic counseling and testing of relatives, and allows potential therapeutic trials. OBJECTIVE: To establish the clinical utility of panel-based whole exome sequencing (WES) in NMDs in a population with children and adults with various neuromuscular symptoms. METHODS: Clinical exome sequencing, followed by diagnostic interpretation of variants in genes associated with NMDs, was performed in a cohort of 396 patients suspected of having a genetic cause with a variable age of onset, neuromuscular phenotype, and inheritance pattern. Many had previously undergone targeted gene testing without results. RESULTS: Disease-causing variants were identified in 75/396 patients (19%), with variants in the three COL6-genes (COL6A1, COL6A2 and COL6A3) as the most common cause of the identified muscle disorder, followed by variants in the RYR1 gene. Together, these four genes account for almost 25% of cases in whom a definite genetic cause was identified. Furthermore, likely pathogenic variants and/or variants of uncertain significance were identified in 95 of the patients (24%), in whom functional and/or segregation analysis should be used to confirm or reject the pathogenicity. In 18% of the cases with a disease-causing variant of which we received additional clinical information, we identified a genetic cause in genes of which the associated phenotypes did not match that of the patients. Hence, the advantage of panel-based WES is its unbiased approach. CONCLUSION: Whole exome sequencing, followed by filtering for NMD genes, offers an unbiased approach for the genetic diagnostics of NMD patients. This approach could be used as a first-tier test in neuromuscular disorders with a high suspicion of a genetic cause. With uncertain results, functional testing and segregation analysis are needed to complete the evidence.

Background Truncating titin variants (TTNtv) are the most prevalent genetic cause of dilated cardiomyopathy, found in ≤25% of familial cases. Moreover, TTNtv associated with dilated cardiomyopathy are estimated to be present in 0.5% of the general population. The prognosis of asymptomatic carriers of TTNtv is poorly understood because TTNtv are associated with a highly variable phenotype. We aim to assess the natural history and clinical relevance of TTNtv by analyzing standardized mortality ratios (SMR) in multigenerational pedigrees and in close relatives of present-day patients. Methods Haplotype and genealogical analyses were performed on 3 recurrent TTNtv. Subsequently, the family tree mortality ratio method was used to compare all-cause mortality of subjects at an a priori 50% risk of carrying TTNtv to the general Dutch population. SMRs were stratified for sex, age, and calendar period. Subgroups were compared with Poisson regression. Similarly, SMRs were calculated in parents of 128 present-day dilated cardiomyopathy probands with TTNtv using the reverse parent-offspring method. Results The TTNtv were established as founder mutations and traced to 18th century ancestors. In 20 522 person-years, overall mortality was not significantly increased (SMR, 1.06; 95% CI, 0.95–1.18; P =0.162). However, mortality was significantly increased in subjects living after 1965 (SMR, 1.27; 95% CI, 1.04–1.53; P =0.009) and aged ≥60 years (SMR, 1.17; 95% CI, 1.01–1.35; P =0.02). The reverse parent-offspring analysis showed overall excess mortality (SMR, 1.26; 95% CI, 1.07–1.48; P =0.003), driven by subjects aged ≥60 years. Conclusions The natural history of the analyzed TTNtv shows a relatively mild disease course with significant excess mortality in elderly patients. With increasing life expectancy, TTNtv-associated morbidity and mortality will likely become more prevalent.

Recent advancements in next generation sequencing (NGS) technology have led to the identification of the giant sarcomere gene, titin (TTN), as a major human disease gene. Truncating variants of TTN (TTNtv) especially in the A-band region account for 20% of dilated cardiomyopathy (DCM) cases. Much attention has been focused on assessment and interpretation of TTNtv in human disease; however, missense and non-frameshifting insertions/deletions (NFS-INDELs) are difficult to assess and interpret in clinical diagnostic workflow. Targeted sequencing covering all exons of TTN was performed on a cohort of 530 primary DCM patients from three cardiogenetic centres across Europe. Using stringent bioinformatic filtering, twenty-nine and two rare TTN missense and NFS-INDELs variants predicted deleterious were identified in 6.98% and 0.38% of DCM patients, respectively. However, when compared with those identified in the largest available reference population database, no significant enrichment of such variants was identified in DCM patients. Moreover, DCM patients and reference individuals had comparable frequencies of splice-region missense variants with predicted splicing alteration. DCM patients and reference populations had comparable frequencies of rare predicted deleterious TTN missense variants including splice-region missense variants suggesting that these variants are not independently causative for DCM. Hence, these variants should be classified as likely benign in the clinical diagnostic workflow, although a modifier effect cannot be excluded at this stage.

Purpose: We aimed to determine the prevalence and phenotypic spectrum of NOTCH1 mutations in left-sided congenital heart disease (LS-CHD). LS-CHD includes aortic valve stenosis, a bicuspid aortic valve, coarctation of the aorta, and hypoplastic left heart syndrome.Methods: NOTCH1 was screened for mutations in 428 nonsyndromic probands with LS-CHD, and family histories were obtained for all. When a mutation was detected, relatives were also tested.Results: In 148/428 patients (35%), LS-CHD was familial. Fourteen mutations (3%; 5 RNA splicing mutations, 8 truncating mutations, 1 whole-gene deletion) were detected, 11 in familial disease (11/148 (7%)) and 3 in sporadic disease (3/280 (1%)). Forty-nine additional mutation carriers were identified among the 14 families, of whom 12 (25%) were asymptomatic. Most of these mutation carriers had LS-CHD, but 9 (18%) had right-sided congenital heart disease (RS-CHD) or conotruncal heart disease (CTD). Thoracic aortic aneurysms (TAAs) occurred in 6 mutation carriers (probands included 6/63 (10%)).Conclusion: Pathogenic mutations in NOTCH1 were identified in 7% of familial LS-CHD and in 1% of sporadic LS-CHD. The penetrance is high; a cardiovascular malformation was found in 75% of NOTCH1 mutation carriers. The phenotypic spectrum includes LS-CHD, RS-CHD, CTD, and TAA. Testing NOTCH1 for an early diagnosis in LS-CHD/RS-CHD/CTD/TAA is warranted.

Objectives To characterise pregnancy course and outcomes in women with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).Methods From a combined Johns Hopkins/Dutch ARVD/C registry, we identified 26 women affected with ARVD/C (by 2010 Task Force Criteria) during 39 singleton pregnancies > 13 weeks (1-4 per woman). Cardiac symptoms, treatment and episodes of sustained ventricular arrhythmias (VAs) and heart failure (HF) >= Class C were characterised. Obstetric outcomes were ascertained. Incidence of VA and HF were compared with rates in the non-pregnant state. Long-term disease course was compared with 117 childbearing-aged female patients with ARVD/C who had not experienced pregnancy with ARVD/C.Results Treatment during pregnancy (n=39) included beta blockers (n=16), antiarrhythmics (n=6), diuretics (n=3) and implantable cardioverter defibrillators (ICDs) (n=28). In five pregnancies (13%), a single VA occurred, including two ICD-terminated events. Arrhythmias occurred disproportionately in probands without VA history (p=0.045). HF, managed on an outpatient basis, developed in two pregnancies (5%) in women with pre-existing overt biventricular or isolated right ventricular disease. All infants were live-born without major obstetric complications. Caesarean sections (n=11, 28%) had obstetric indications, except one (HF). beta Blocker therapy was associated with lower birth weight (3.1 +/- 0.48 kg vs 3.7 +/- 0.57 kg; p=0.002). During follow-up children remained healthy (median 3.4 years), and mothers were without cardiac mortality or transplant. Neither VA nor HF incidence was significantly increased during pregnancy. ARVD/C course (mean 6.5 +/- 5.6 years) did not differ based on pregnancy history.Conclusions While most pregnancies in patients with ARVD/C were tolerated well, 13% were complicated by VA and 5% by HF.

BACKGROUND Cardiomyopathies are usually inherited and predominantly affect adults, but they can also present in childhood. Although our understanding of the molecular basis of pediatric cardiomyopathy has improved, the underlying mechanism remains elusive in a substantial proportion of cases.OBJECTIVES This study aimed to identify new genes involved in pediatric cardiomyopathy.METHODS The authors performed homozygosity mapping and whole-exome sequencing in 2 consanguineous families with idiopathic pediatric cardiomyopathy. Sixty unrelated patients with pediatric cardiomyopathy were subsequently screened for mutations in a candidate gene. First-degree relatives were submitted to cardiac screening and cascade genetic testing. Myocardial samples from 2 patients were processed for histological and immunohistochemical studies.RESULTS We identified 5 patients from 3 unrelated families with pediatric cardiomyopathy caused by homozygous truncating mutations in ALPK3, a gene encoding a nuclear kinase that plays an essential role in early differentiation of cardiomyocytes. All patients with biallelic mutations presented with severe hypertrophic and/or dilated cardiomyopathy in utero, at birth, or in early childhood. Three patients died from heart failure within the first week of life. Moreover, 2 of 10 (20%) heterozygous family members showed hypertrophic cardiomyopathy with an atypical distribution of hypertrophy. Deficiency of alpha-kinase 3 has previously been associated with features of both hypertrophic and dilated cardiomyopathy in mice. Consistent with studies in knockout mice, we provide microscopic evidence for intercalated disc remodeling.CONCLUSIONS Biallelic truncating mutations in the newly identified gene ALPK3 give rise to severe, early-onset cardiomyopathy in humans. Our findings highlight the importance of transcription factor pathways in the molecular mechanisms underlying human cardiomyopathies. (C) 2016 by the American College of Cardiology Foundation.

We report two unrelated patients with a multisystem disease involving liver, eye, immune system, connective tissue, and bone, caused by biallelic mutations in the neuroblastoma amplified sequence (NBAS) gene. Both presented as infants with recurrent episodes triggered by fever with vomiting, dehydration, and elevated transaminases. They had frequent infections, hypogammaglobulinemia, reduced natural killer cells, and the Pelger-Huet anomaly of their granulocytes. Their facial features were similar with a pointed chin and proptosis; loose skin and reduced subcutaneous fat gave them a progeroid appearance. Skeletal features included short stature, slender bones, epiphyseal dysplasia with multiple phalangeal pseudo-epiphyses, and small C1-C2 vertebrae causing cervical instability and myelopathy. Retinal dystrophy and optic atrophy were present in one patient. NBAS is a component of the synthaxin-18 complex and is involved in nonsense-mediated mRNA decay control. Putative loss-of-function mutations in NBAS are already known to cause disease in humans. A specific founder mutation has been associated with short stature, optic nerve atrophy and Pelger-Huet anomaly of granulocytes (SOPH) in the Siberian Yakut population. A more recent report associates NBAS mutations with recurrent acute liver failure in infancy in a group of patients of European descent. Our observations indicate that the phenotypic spectrum of NBAS deficiency is wider than previously known and includes skeletal, hepatic, metabolic, and immunologic aspects. Early recognition of the skeletal phenotype is important for preventive management of cervical instability.

Peripartum cardiomyopathy (PPCM) and dilated cardiomyopathy (DCM) show similarities in clinical presentation. However, although DCM patients do not recover and slowly deteriorate further, PPCM patients show either a fast cardiac deterioration or complete recovery. The aim of this study was to assess if underlying cellular changes can explain the clinical similarities and differences in the two diseases. We, therefore, assessed sarcomeric protein expression, modification, titin isoform shift, and contractile behavior of cardiomyocytes in heart tissue of PPCM and DCM patients and compared these with nonfailing controls. Heart samples from ischemic heart disease (ISHD) patients served as heart failure control samples. Passive force was only increased in PPCM samples compared with controls, whereas PPCM, DCM, and ISHD samples all showed increased myofilament Ca2+ sensitivity. Length-dependent activation was significantly impaired in PPCM compared with controls, no impairment was observed in ISHD samples, and DCM samples showed an intermediate response. Contractile impairments were caused by impaired protein kinase A (PKA)–mediated phosphorylation because exogenous PKA restored all parameters to control levels. Although DCM samples showed reexpression of EH-myomesin, an isoform usually only expressed in the heart before birth, PPCM and ISHD did not. The lack of EH-myomesin, combined with low PKA-mediated phosphorylation of myofilament proteins and increased compliant titin isoform, may explain the increase in passive force and blunted length-dependent activation of myofilaments in PPCM samples.

BACKGROUND The clinical outcomes of noncompaction cardiomyopathy (NCCM) range from asymptomatic to heart failure, arrhythmias, and sudden cardiac death. Genetics play an important role in NCCM.OBJECTIVES This study investigated the correlations among genetics, clinical features, and outcomes in adults and children diagnosed with NCCM.METHODS A retrospective multicenter study from 4 cardiogenetic centers in the Netherlands classified 327 unrelated NCCM patients into 3 categories: 1) genetic, with a mutation in 32% (81 adults; 23 children) of patients; 2) probably genetic, familial cardiomyopathy without a mutation in 16% (45 adults; 8 children) of patients; or 3) sporadic, no family history, without mutation in 52% (149 adults; 21 children) of patients. Clinical features and major adverse cardiac events (MACE) during follow-up were compared across the children and adults.RESULTS MYH7, MYBPC3, and TTN mutations were the most common mutations (71%) found in genetic NCCM. The risk of having reduced left ventricular (LV) systolic dysfunction was higher for genetic patients compared with the probably genetic and sporadic cases (p = 0.024), with the highest risk in patients with multiple mutations and TTN mutations. Mutations were more frequent in children (p = 0.04) and were associated with MACE (p = 0.025). Adults were more likely to have sporadic NCCM. High risk for cardiac events in children and adults was related to LV systolic dysfunction in mutation carriers, but not in sporadic cases. Patients with MYH7 mutations had low risk for MACE (p = 0.03).CONCLUSIONS NCCM is a heterogeneous condition, and genetic stratification has a role in clinical care. Distinguishing genetic from nongenetic NCCM complements prediction of outcome and may lead to management and follow-up tailored to genetic status. (c) 2018 by the American College of Cardiology Foundation.

Genetic studies in the 1980s and 1990s led to landmark discoveries that sarcomere mutations cause both hypertrophic and dilated cardiomyopathies. Sarcomere mutations also likely play a role in more complex phenotypes and overlap cardiomyopathies with features of hypertrophy, dilation, diastolic abnormalities, and non-compaction. Identification of the genetic cause of these important conditions provides unique opportunities to interrogate and characterize disease pathogenesis and pathophysiology, starting from the molecular level and expanding from there. With such insights, there is potential for clinical translation that may transform management of patients and families with inherited cardiomyopathies. If key pathways for disease development can be identified, they could potentially serve as targets for novel disease-modifying or disease-preventing therapies. By utilizing gene-based diagnostic testing, we can identify at-risk individuals prior to the onset of clinical disease, allowing for disease-modifying therapy to be initiated early in life, at a time that such treatment may be most successful. In this section, we review the current application of genetics in clinical management, focusing on hypertrophic cardiomyopathy as a paradigm; discuss state-of-the-art genetic testing technology; review emerging knowledge of gene expression in sarcomeric cardiomyopathies; and discuss both the prospects, as well as the challenges, of bringing genetics to medicine.

Background— Interpretation of missense variants can be especially difficult when the variant is also found in control populations. This is what we encountered for the LMNA c.992G>A (p.(Arg331Gln)) variant. Therefore, to evaluate the effect of this variant, we combined an evaluation of clinical data with functional experiments and morphological studies. Methods and Results— Clinical data of 23 probands and 35 family members carrying this variant were retrospectively collected. A time-to-event analysis was performed to compare the course of the disease with carriers of other LMNA mutations. Myocardial biopsies were studied with electron microscopy and by measuring force development of the sarcomeres. Morphology of the nuclear envelope was assessed with immunofluorescence on cultured fibroblasts. The phenotype in probands and family members was characterized by atrioventricular conduction disturbances (61% and 44%, respectively), supraventricular arrhythmias (69% and 52%, respectively), and dilated cardiomyopathy (74% and 14%, respectively). LMNA p.(Arg331Gln) carriers had a significantly better outcome regarding the composite end point (malignant ventricular arrhythmias, end-stage heart failure, or death) compared with carriers of other pathogenic LMNA mutations. A shared haplotype of 1 Mb around LMNA suggested a common founder. The combined logarithm of the odds score was 3.46. Force development in membrane-permeabilized cardiomyocytes was reduced because of decreased myofibril density. Structural nuclear LMNA -associated envelope abnormalities, that is, blebs, were confirmed by electron microscopy and immunofluorescence microscopy. Conclusions— Clinical, morphological, functional, haplotype, and segregation data all indicate that LMNA p.(Arg331Gln) is a pathogenic founder mutation with a phenotype reminiscent of other LMNA mutations but with a more benign course.

Pediatric cardiomyopathy is a rare but severe disease with high morbidity and mortality. The causes are poorly understood and can only be established in one-third of cases. Recent advances in genetic technologies, specifically next-generation sequencing, now allow for the detection of genetic causes of cardiomyopathy in a systematic and unbiased manner. This is particularly important given the large clinical variability among pediatric cardiomyopathy patients and the large number of genes (>100) implicated in the disorder. We report on the performance of whole-exome sequencing in members of a consanguineous family with a history of pediatric hypertrophic cardiomyopathy and sudden cardiac death, which led to the identification of a homozygous stop variant in the SLC22A5 gene, implicated in primary carnitine deficiency, as the likely genetic cause. Targeted carnitine tandem mass spectrometry analysis in the patient revealed complete absence of plasma-free carnitine and only trace levels of total carnitine, further supporting the causality of the SLC22A5 variant. l-carnitine supplementation in the proband led to a rapid and marked clinical improvement. This case illustrates the use of exome sequencing as a systematic and unbiased diagnostic tool in pediatric cardiomyopathy, providing an efficient route to the identification of the underlying cause, which lead to appropriate treatment and prevention of premature death.

Aim Peripartum cardiomyopathy (PPCM) can be an initial manifestation of familial dilated cardiomyopathy (DCM). We aimed to identify mutations in families that could underlie their PPCM and DCM.Methods and results We collected 18 families with PPCM and DCM cases from various countries. We studied the clinical characteristics of the PPCM patients and affected relatives, and applied a targeted next-generation sequencing (NGS) approach to detect mutations in 48 genes known to be involved in inherited cardiomyopathies. We identified 4 pathogenic mutations in 4 of 18 families (22%): 3 in TTN and 1 in BAG3. In addition, we identified 6 variants of unknown clinical significance that may be pathogenic in 6 other families (33%): 4 in TTN, 1 in TNNC1, and 1 in MYH7. Measurements of passive force in single cardiomyocytes and titin isoform composition potentially support an upgrade of one of the variants of unknown clinical significance in TTN to a pathogenic mutation. Only 2 of 20 PPCM cases in these families showed the recovery of left ventricular function.Conclusion Targeted NGS shows that potentially causal mutations in cardiomyopathy-related genes are common in families with both PPCM and DCM. This supports the earlier finding that PPCM can be part of familial DCM. Our cohort is particularly characterized by a high proportion of TTN mutations and a low recovery rate in PPCM cases.

Background The EURObservational Research Programme is a rolling programme of cardiovascular registries and surveys of the European Society of Cardiology (ESC). These registries will provide information on the nature of cardiovascular disease and its management. This manuscript provides an update on new literature on peripartum cardiomyopathy (PPCM), published since the 2010 Position Statement from the Heart Failure Association of the European Society of Cardiology Working Group on PPCM, and describes a new registry on this under-recognized condition. Peripartum cardiomyopathy is an idiopathic cardiomyopathy presenting with heart failure secondary to left ventricular systolic dysfunction towards the end of the pregnancy, or in the months following delivery, where no other cause for heart failure is found. Aims The PPCM Registry aims to describe disease presentation, comorbidities, diagnostic and therapeutic management of patients with PPCM, as well as information on their offspring. Centres not only from ESC and ESC-affiliated countries, but from around the world, are encouraged to participate. Methods A prospective registry on patients presenting with PPCM. At the time of writing, approximately 100 patients have been enrolled from 20 countries. All data entry is online via secure passwords and is supported by well-trained information technology personnel. Conclusion The EURObservational Research Programme will allow a comparison of women from around the world, from different ethnic backgrounds, presenting with PPCM and will report on their 6 month and 12 month outcomes. The study aims to include 1000 patients and follow them for 1 year. New centres volunteering to participate in the study will be welcomed.

With more than 40 dilated cardiomyopathy (DCM)-related genes known, genetic analysis of patients with idiopathic DCM is costly and time-consuming. We describe the yield from genetic analysis in DCM patients in a large Dutch cohort. We collected cardiological and neurological evaluations, family screenings, and genetic analyses for 418 index patients with idiopathic DCM. We identified 35 (putative) pathogenic mutations in 82 index patients (20%). The type of DCM influenced the yield, with mutations found in 25% of familial DCM cases, compared with 8% of sporadic DCM cases and 62% of cases where DCM was accompanied by neuromuscular disease. A PLN founder mutation (43 cases) and LMNA mutations (19 cases, 16 different mutations) were most prevalent and often demonstrated a specific phenotype. Other mutations were found in: MYH7, DES, TNNT2, DMD, TPM1, DMPK, SCN5A, SGCB (homozygous), and TNNI3. After a median follow-up of 40 months, the combined outcome of death from any cause, heart transplantation, or malignant ventricular arrhythmias in patients with a mutation was worse than in those without an identified mutation (hazard ratio 2.0, 95% confidence interval 1.4-3.0). This seems to be mainly attributable to a high prevalence of malignant ventricular arrhythmias and end-stage heart failure in LMNA and PLN mutation carriers. The yield of identified mutations in DCM index patients with clinical clues, such as associated neuromuscular disease or familial occurrence, is higher compared with those without these clues. For sporadic DCM, specific clinical characteristics may be used to select cases for DNA analysis

Truncating titin mutations (tTTN) occur in 25% of dilated cardiomyopathy (DCM) cases, but the phenotype and severity of disease they cause have not yet been systematically studied. We studied whether tTTN variants are associated with a clinically distinguishable form of DCM.We compared clinical data on DCM probands and relatives with a tTTN mutation (n = 45, n = 73), LMNA mutation (n = 28, n = 29), and probands who tested negative for both genes [idiopathic DCM (iDCM); n = 60]. Median follow-up was at least 2.5 years in each group. TTN subjects presented with DCM at higher age than LMNA subjects (probands 47.9 vs. 40.4 years, P = 0.004; relatives 59.8 vs. 47.0 years, P = 0.01), less often developed LVEF35% [probands hazard ratio (HR) 0.38, P = 0.002], had higher age of death (probands 70.4 vs. 59.4 years, P0.001; relatives 74.1 vs. 58.4 years, P = 0.008), and had better composite outcome (malignant ventricular arrhythmia, heart transplantation, or death; probands HR 0.09, P0.001; relatives HR 0.21, P = 0.02) than LMNA subjects and iDCM subjects (HR 0.36, P = 0.07). An LVEF increase of at least 10% occurred in 46.9% of TTN subjects after initiation of standard heart failure treatment, while this only occurred in 6.5% of LMNA subjects (P0.001) and 18.5% of iDCM subjects (P = 0.02). This was confirmed in families with co-segregation, in which the 10% point LVEF increase occurred in 55.6% of subjects (P = 0.003 vs. LMNA, P = 0.079 vs. iDCM).This study shows that tTTN-associated DCM is less severe at presentation and more amenable to standard therapy than LMNA mutation-induced DCM or iDCM.

Item does not contain fulltext Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant syndrome characterized by skin piloleiomyomas, uterine leiomyomas and papillary type 2 renal cancer caused by germline mutations in the fumarate hydratase (FH) gene. Previously, we proposed renal imaging for FH mutation carriers starting at the age of 20 years. However, recently an 18-year-old woman from a Dutch family with HLRCC presented with metastatic renal cancer. We describe the patient and family data, evaluate current evidence on renal cancer risk and surveillance in HLRCC and consider the advantages and disadvantages of starting surveillance for renal cancer in childhood. We also discuss the targeted therapies administered to our patient.

Cardiomyopathies (CMP) in children are heterogeneous disorders of cardiac muscle with a relatively high incidence in infancy (8/100.000) as compared to older children (0.7/100.000). Beyond infancy, CMP is the most important indication for heart transplantation and transplantation free survival at 5 years after initial diagnosis is only 54%. Mutations in over 65 genes encoding sarcomeric, cytoskeletal and calcium-metabolizing proteins, cell-signaling molecules, and mitochondrial enzymes have been shown to cause CMPs. This has led to new recommendations for diagnostic evaluation and family screening incorporating genetic testing. However, present (targeted/custom based) diagnostic tests do not represent the whole spectrum of genetic etiologies and are leading to a correct diagnosis in just a subset of pediatric CMP patients. We present four children from two consanguineous families of Dutch and Moroccan descent with severe neonatal onset of CMP, ranging from lethal cardiomegaly with reduced contractility in three to severe left ventricular hypertrophy that remained stable in one child. A combined approach using homozygosity mapping and exome sequencing in both families identified a homozygous splice site variant resulting in exon skipping in the Dutch family, and a homozygous nonsense mutation in the Moroccan family within the same gene. This novel disease causing gene is implicated in the early differentiation of cardiomyocytes. Both variants were confirmed with Sanger sequencing and absent in large control populations. Previously published studies in a knockout mouse model demonstrated the functional role of this gene in CMPs. Additionally, we investigated the effect of the homozygous splice site mutation on the expression of different proteins at myocardial cell-cell junctions and myofibrils. These results point towards a role in intercalated disk remodeling. Electron microscopy- and protein expression studies on heart tissue of the patients are ongoing. Our findings add a new autosomal recessive gene to the list of genes already implicated in pediatric CMP, underscoring its genetic heterogeneity. Furthermore, our study indicates that the application of exome sequencing can improve the diagnostic yield in pediatric CMP.

Pregnancy exposes women with inherited cardiomyopathies to increased risk for heart failure and arrhythmias. In this paper, we review the clinical course and management of pregnant women with the following inherited cardiomyopathies: hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular non-compaction cardiomyopathy, and restrictive cardiomyopathy. We also discuss peripartum cardiomyopathy. Pregnancy is generally well tolerated in asymptomatic patients with inherited cardiomyopathies. However, worsening of the clinical condition can occur during pregnancy, despite intensive medical treatment. If prior cardiac events, poor functional class (New York Heart Association class III or IV), or advanced left ventricular systolic dysfunction are present, the risk of maternal cardiac complications during pregnancy are markedly increased. The postpartum condition is generally no worse than the antepartum condition, but no long-term follow-up studies have been reported. Preconception evaluation and counselling are important aspects of managing women with inherited cardiomyopathies. Genetic counselling and DNA testing should be offered to all women following the diagnosis of an inherited cardiomyopathy.

BACKGROUND Desmin-related myopathy is a clinically heterogenous group of disorders encompassing myopathies, cardiomyopathies, conduction disease, and combinations of these disorders. Mutations in the gene encoding desmin (DES), a major intermediate filament protein, can underlie this phenotype.OBJECTIVE The purpose of this study was to investigate the clinical and pathologic characteristics of 27 patients from five families with an identical mutation in the head domain region (p.S13F) of desmin.METHODS/RESULTS ALL 27 carriers or obligate carriers of a p.S13F DES founder mutation demonstrated a fully penetrant yet variable phenotype. ALL patients demonstrated cardiac involvement characterized by high-grade AV block at young ages and important right ventricular (RV) involvement. RV predominance was demonstrated by the presence of right bundle branch block in 10 patients (sometimes as a first manifestation) and by RV heart failure in 6 patients, including 2 patients who fulfilled the diagnostic criteria for arrhythmogenic RV cardiomyopathy. Because of this clinical overlap with desmosome cardiomyopathies, we also studied the organization of the intercalated disks, particularly the distribution of desmosomal proteins. Normal amounts of the major desmosomal proteins were found, but the intercalated disks were more convoluted and elongated and had a zigzag appearance.CONCLUSION In this Largest series to date of individuals with a single head domain DES mutation, patients show a variable yet predominantly cardiologic phenotype characterized by conduction disease at an early age and RV involvement including right bundle branch block and/or RV tachycardias and arrhythmogenic RV cardiomyopathy phenocopies. A Localized effect of desmin on the structure of the cardiac intercalated disks might contribute to disease pathogenesis.

Most hypertrophic cardiomyopathies and a subset of dilated and arrhythmogenic right ventricular cardiomyopathies are familial diseases. They generally show an autosomal dominant pattern of inheritance and have underlying mutations in genes encoding sarcomeric, cytoskeletal, nuclear envelope, and desmosomal proteins. DNA analysis in cardiomyopathies can help diagnose borderline cases, and cascade screening of family members can identify individuals at risk. Genotype-phenotype relations are complex, but some associations, such as septal morphology, electrocardiogram parameters, and additional cardiac and other manifestations, point toward certain genes. Such features help target DNA testing and the results of DNA analysis can be used in making clinical decisions.

Although familial forms of cardiomyopathy such as hypertrophic or dilated cardiomyopathy have been recognized for decades, it is only recently that much of the genetic basis of these inherited cardiomyopathies has been elucidated. This has provided important insights into the pathophysiological mechanisms underlying the disease phenotype. This increased knowledge and the availability of genetic testing has resulted in increasing numbers of mutation carriers who are being monitored, including many who are now of child-bearing age. Pregnancy is generally well tolerated in asymptomatic patients or mutation carriers with inherited cardiomyopathies. However, since pregnancy leads to major physiological changes in the cardiovascular system, in women with genetic cardiomyopathies or who carry a mutation pre-disposing to a genetic cardiomyopathy, pregnancy entails a risk of developing heart failure and/or arrhythmias. This deterioration of cardiac function may occur despite optimal medical treatment. Advanced left ventricular dysfunction, poor functional class (NYHA class III or IV), or prior cardiac events appear to increase the risk of maternal cardiac complications. However, there are no large series of cardiomyopathy patients who are regularly evaluated for cardiac complications during pregnancy and for certain types of inherited cardiomyopathy, only case reports on individual pregnancies are available. Pre-conception cardiologic evaluation and genetic counselling are important for every woman with a cardiomyopathy or a cardiomyopathy-related mutation who is considering having a family. In this article, we give an overview of the basic clinical aspects, genetics, and pregnancy outcome in women with different types of inherited cardiomyopathies. We also discuss the genetic aspects of pregnancy-associated cardiomyopathy, including peripartum cardiomyopathy.

PMP22 related neuropathies comprise (1) PMP22 duplications leading to Charcot-Marie-Tooth disease type 1A (CMT1A), (2) PMP22 deletions, leading to Hereditary Neuropathy with liability to Pressure Palsies (HNPP), and (3) PMP22 point mutations, causing both phenotypes. Overall prevalence of CMT is usually reported as 1:2,500, epidemiological studies show that 20-64% of CMT patients carry the PMP22 duplication. The prevalence of HNPP is not well known. CMT1A usually presents in the first two decades with difficulty walking or running. Distal symmetrical muscle weakness and wasting and sensory loss is present, legs more frequently and more severely affected than arms. HNPP typically leads to episodic, painless, recurrent, focal motor and sensory peripheral neuropathy, preceded by minor compression on the affected nerve. Electrophysiological evaluation is needed to determine whether the polyneuropathy is demyelinating. Sonography of the nerves can be useful. Diagnosis is confirmed by finding respectively a PMP22 duplication, deletion or point mutation. Differential diagnosis includes other inherited neuropathies, and acquired polyneuropathies. The mode of inheritance is autosomal dominant and de novo mutations occur. Offspring of patients have a chance of 50% to inherit the mutation from their affected parent. Prenatal testing is possible; requests for prenatal testing are not common. Treatment is currently symptomatic and may include management by a rehabilitation physician, physiotherapist, occupational therapist and orthopaedic surgeon. Adult CMT1A patients show slow clinical progression of disease, which seems to reflect a process of normal ageing. Life expectancy is normal.

Mutation detection through exome sequencing allows simultaneous analysis of all coding sequences of genes. However, it cannot yet replace Sanger sequencing (SS) in diagnostics because of incomplete representation and coverage of exons leading to missing clinically relevant mutations. Targeted next-generation sequencing (NGS), in which a selected fraction of genes is sequenced, may circumvent these shortcomings. We aimed to determine whether the sensitivity and specificity of targeted NGS is equal to those of SS. We constructed a targeted enrichment kit that includes 48 genes associated with hereditary cardiomyopathies. In total, 84 individuals with cardiomyopathies were sequenced using 151bp paired-end reads on an Illumina MiSeq sequencer. The reproducibility was tested by repeating the entire procedure for five patients. The coverage of 30 reads per nucleotide, our major quality criterion, was 99% and in total approximate to 21,000 variants were identified. Confirmation with SS was performed for 168 variants (155 substitutions, 13 indels). All were confirmed, including a deletion of 18bp and an insertion of 6bp. The reproducibility was nearly 100%. We demonstrate that targeted NGS of a disease-specific subset of genes is equal to the quality of SS and it can therefore be reliably implemented as a stand-alone diagnostic test.

Item does not contain fulltext A cardioskeletal myopathy with onset and death in infancy, morphological features of muscle type I hypotrophy with myofibrillar disorganization and dilated cardiomyopathy was previously reported in three Dutch families. Here we report the genetic cause of this disorder. Multipoint parametric linkage analysis of six Dutch patients identified a homozygous region of 2.1 Mb on chromosome 12, which was shared between all Dutch patients, with a log of odds score of 10.82. Sequence analysis of the entire linkage region resulted in the identification of a homozygous mutation in the last acceptor splice site of the myosin regulatory light chain 2 gene (MYL2) as the genetic cause. MYL2 encodes a myosin regulatory light chain (MLC-2V). The myosin regulatory light chains bind, together with the essential light chains, to the flexible neck region of the myosin heavy chain in the hexameric myosin complex and have a structural and regulatory role in muscle contraction. The MYL2 mutation results in use of a cryptic splice site upstream of the last exon causing a frameshift and replacement of the last 32 codons by 20 different codons. Whole exome sequencing of an Italian patient with similar clinical features showed compound heterozygosity for two other mutations affecting the same exon of MYL2, also resulting in mutant proteins with altered C-terminal tails. As a consequence of these mutations, the second EF-hand domain is disrupted. EF-hands, assumed to function as calcium sensors, can undergo a conformational change upon binding of calcium that is critical for interactions with downstream targets. Immunohistochemical staining of skeletal muscle tissue of the Dutch patients showed a diffuse and weak expression of the mutant protein without clear fibre specificity, while normal protein was absent. Heterozygous missense mutations in MYL2 are known to cause dominant hypertrophic cardiomyopathy; however, none of the parents showed signs of cardiomyopathy. In conclusion, the mutations in the last exon of MYL2 are responsible for a novel autosomal recessive lethal myosinopathy due to defects changing the C-terminal tail of the ventricular form of the myosin regulatory light chain. We propose 'light chain myopathy' as a name for this MYL2-associated myopathy.

Aims To investigate whether phospholamban gene (PLN) mutations underlie patients diagnosed with either arrhythmogenic right ventricular cardiomyopathy (ARVC) or idiopathic dilated cardiomyopathy (DCM). Methods and results We screened a cohort of 97 ARVC and 257 DCM unrelated index patients for PLN mutations and evaluated their clinical characteristics. PLN mutation R14del was identified in 12 (12 %) ARVC patients and in 39 (15 %) DCM patients. Haplotype analysis revealed a common founder, estimated to be between 575 and 825 years old. A low voltage electrocardiogram was present in 46 % of R14del carriers. Compared with R14del– DCM patients, R14del+ DCM patients more often demonstrated appropriate implantable cardioverter defibrillator discharge (47 % vs. 10 %, P < 0.001), cardiac transplantation (18 % vs. 2 %, P < 0.001), and a family history for sudden cardiac death (SCD) at < 50 years (36 % vs. 16 %, P = 0.007). We observed a similar pattern in the ARVC patients although this was not statistically significant. The average age of 26 family members who died of SCD was 37.7 years. Immunohistochemistry in available myocardial samples revealed absent/depressed plakoglobin levels at intercalated disks in five of seven (71 %) R14del+ ARVC samples, but in only one of nine (11 %) R14del+ DCM samples (P = 0.03). Conclusions The PLN R14del founder mutation is present in a substantial number of patients clinically diagnosed with DCM or ARVC. R14del+ patients diagnosed with DCM showed an arrhythmogenic phenotype, and SCD at young age can be the presenting symptom. These findings support the concept of ‘arrhythmogenic cardiomyopathy’.

Legius syndrome presents as an autosomal dominant condition characterized by cafe-au-lait macules with or without freckling and sometimes a Noonan-like appearance and/ or learning difficulties. It is caused by germline loss-of-function SPRED1 mutations and is a member of the RAS-MAPK pathway syndromes. Most mutations result in a truncated protein and only a few inactivating missense mutations have been reported. Since only a limited number of patients has been reported up until now, the full clinical and mutational spectrum is still unknown. We report mutation data and clinical details in fourteen new families with Legius syndrome. Six novel germline mutations are described. The Trp31Cys mutation is a new pathogenic SPRED1 missense mutation. Clinical details in the 14 families confirmed the absence of neurofibromas, and Lisch nodules, and the absence of a high prevalence of central nervous system tumors. We report white matter T2 hyperintensities on brain MRI scans in 2 patients and a potential association between postaxial polydactyly and Legius syndrome. (C) 2010 Wiley-Liss, Inc.

Background— Anecdotal cases of familial clustering of peripartum cardiomyopathy (PPCM) and familial occurrences of PPCM and idiopathic dilated cardiomyopathy (DCM) together have been observed, suggesting that genetic factors play a role in the pathogenesis of PPCM. We hypothesized that some cases of PPCM are part of the spectrum of familial DCM, presenting in the peripartum period. Methods and Results— We reviewed our database of 90 DCM families, focusing specifically on the presence of PPCM patients. Then, in a reverse approach, we reviewed 10 PPCM patients seen in our clinic since the early 1990s and performed cardiological screening of the first-degree relatives of 3 PPCM patients who did not show a full recovery. Finally, we analyzed the genes known to be most commonly involved in DCM in the PPCM patients. We identified a substantial number (5 of 90, 6%) of DCM families with PPCM patients. Second, cardiological screening of first-degree relatives of 3 PPCM patients who did not show full recovery revealed undiagnosed DCM in all 3 families. Finally, genetic analyses revealed a mutation (c.149A>G, p.Gln50Arg) in the gene encoding cardiac troponin C ( TNNC1 ) segregating with disease in a DCM family with a member with PPCM, supporting the genetic nature of disease in this case. Conclusions— Our findings strongly suggest that a subset of PPCM is an initial manifestation of familial DCM. This may have important implications for cardiological screening in such families.

Aims We investigated the presence of a clinical diagnosis of hypertrophic cardiomyopathy (HCM) and of risk factors for sudden cardiac death (SCD) at the first cardiological evaluation after predictive genetic testing in asymptomatic carriers of an MYBPC3 gene mutation.Methods and results Two hundred and thirty-five mutation carriers were cardiologically evaluated on the presence of HCM and risk factors. A clinical diagnosis of HCM was made in 53 carriers (22.6%). Disease penetrance at 65 years was incomplete for all types of MYBPC3 gene mutations. Women were affected less often than men (15 and 32% respectively, P = 0.003) and disease penetrance was lower in females than in males (13 and 30% at 50 years, respectively, P = 0.024). One risk factor was present in 87 carriers and 9 had two or more risk factors. Twenty-five carriers (11%) with one or more risk factors and manifest HCM could be at risk for SCD.Conclusion At first cardiological evaluation almost one-quarter of asymptomatic carriers was diagnosed with HCM. Risk factors for SCD were frequently present and 11% of carriers could be at risk for SCD. Predictive genetic testing in HCM families and frequent cardiological evaluation on the presence of HCM and risk factors for SCD are justified until advanced age.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34 or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR). Here we investigate the effects of putative TSC1 missense mutations identified in individuals with signs and/or symptoms of TSC on TSC1-TSC2 complex formation and mTOR signalling. We show that specific amino-acid substitutions close to the N-terminal of TSC1 reduce steady-state levels of TSC1, resulting in the activation of mTOR signalling and leading to the symptoms of TSC.

Most hypertrophic cardiomyopathies and a subset of dilated and arrhythmogenic right ventricular cardiomyopathies are familial diseases. They generally show an autosomal dominant pattern of inheritance and have underlying mutations in genes encoding sarcomeric, cytoskeletal, nuclear envelope, and desmosomal proteins. DNA analysis in cardiomyopathies can help diagnose borderline cases, and cascade screening of family members can identify individuals at risk. Genotype-phenotype relations are complex, but some associations, such as septal morphology, electrocardiogram parameters, and additional cardiac and other manifestations, point toward certain genes. Such features help target DNA testing and the results of DNA analysis can be used in making clinical decisions.

OBJECTIVE: Anthracyclines are successfully used in cancer treatment, but their use is limited by their cardiotoxic side effects. Several risk factors for anthracycline-associated cardiomyopathy (AACM) are known, yet the occurrence of AACM in the absence of these known risk factors suggests that other factors must play a role. The purpose of this study was to evaluate whether a genetic predisposition for dilated cardiomyopathy (DCM) could be a potential risk factor for AACM.METHODS: A hospital-based registry of 162 DCM families and two hospital-based registries of patients with cancer treated with systemic cancer therapy (n>6000) were reviewed focusing on AACM. Selected patients with AACM/DCM families with possible AACM (n=21) were analysed for mutations in cardiomyopathy-associated genes and presymptomatic cardiological evaluation of first-degree relatives was performed.RESULTS: We identified five DCM families with AACM and one patient with AACM with a family member with a possible early sign of mild DCM. Pathogenic MYH7 mutations were identified in two of these six families. The MYH7 c.1633G>A (p.Asp545Asn) and c.2863G>A (p.Asp955Asn) mutations (one double mutant allele) were identified in a DCM family with AACM. The MYH7 c.4125T>A (p.Tyr1375X) mutation was identified in one patient with AACM.CONCLUSIONS: This study further extends the hypothesis that a genetic predisposition to DCM could be a potential risk factor for AACM.